Retrofitting Cruise Control
Fitting a cruise control system is a great way to improve the driveability of your E30. Here's how.
Contents
Parts
- Cruise control actuator 65 71 1 386 242.9
- Cruise control actuator bracket 65 71 1 386 226
- Cruise control wiring loom
- Cruise control control lever 1 370 162
- Cruise control ECU 65 71 1 386 189
- Cruise control ECU bracket (optional)
- Clutch switch (optional, manual only) 61 31 8 360 421
- Clutch switch bracket (optional, manual only) 35 11 1 157 815
- Clutch switch bypass (required for automatic)
- Ground lead to attach to wiring harness
- Instrument cluster multi-function plug
- Nuts, bolts, screws for all the above
Fitting
Actuator
The control cable is routed along the passenger side of the engine compartment, and enters the passenger compartment through the firewall under the fuse panel. To get to the connector, you need to look underneath the glove box. This may be a very tight fit which may necessitate removing the glove box. Either way, once you've got a clear view, look where the rest of the wiring goes through the firewall and you’ll see some circular cutouts in the rubber grommet. You need to remove the smallest of these, and push through the actuator cable plug from the engine bay into the footwell.
Next we’ll connect the throttle cable. This cable is routed along the driver’s side shock tower to the throttle arm. There is a cable guide bolted to the shock tower to secure it. There is also a plastic insert (A) that clips into a bracket to hold the cable’s jacket to the engine. This insert gets brittle with time, and will likely break if you don't treat it carefully. If it does break, you'll have to replace the cruise control cable.
Once the cable body is clipped in place, you need to connect the cable end to the throttle arm. On the throttle arm you should see a square cutout, just like the one that's holding the existing throttle cable. You need to undo the nut on the cable and remove the sleeve, then get the plastic clip into the square cutout before refitting the plastic sleeve.
Finally, we’ll mount the actuator. The servo should already be mounted to its bracket using three M5 nuts; if not, do that now. Then offer the actuator up to the two studs on the AFM mount, and bolt the actuator in place.
Loom
Before we can fit the harness, we have to do a few things.
The steering wheel HAS to be off. Once you've done that, remove the lower steering column trim (4 phillips / pozidrive screws, M5, two at the wheel, two in the well by the end of the trim).
Next, remove the instrument cluster. Reach behind the cluster and find two (one on each side) M5 thumbscrews that hold the small piece of trim between the top of the steering column and the bottom of the cluster. Unscrew these and push the studs that they were on outwards, the trim will pop out towards the seat. You now have access to the cluster bezel, which is held in place by four black Phillips screws. Once the bezel is off, the cluster is held by two silver Phillips screws. Once these are removed, the cluster can be tilted forward from the top to be removed. Note, if the cluster is in good condition, place a rag on the steering column so the cluster glass doesn’t get scratched (you never know, since it’s out, you might want it as a replacement).
You also need to get the ECU out to fit the cruise ECU above it.
Having done all that, you can now install the loom. This part is tricky. If you have long, slim arms you can possibly push the cables through behind the radio to get to the bulkhead connector. For the rest of us, remove the radioso that you can feed the cables across and behind the dash more easily. Note, an M2 or 2.5 allen key will open the 5-sided socket screws that holds the radio in place.
ECU
Having done all that, you can now fit the ECU and one side of the harness. Start by connecting the blue plug to the ECU before trying to mount the ECU; trying to plug blue connector in place afterwards is a nightmare. Once it's plugged in, the cruise ECU, with bracket, bolts in place above the existing ECU but since it's so fiddly to do this, many people find it much easier just to stuff the cruise ECU into the mass of wires in such a way that it can't move.
Green Plug
Look at the back of the cluster. You should see some square holes in the middle, which correspond exactly to the green plug you have in your hand. All you need to do is to push the green plug into those holes to make the connection.
Plugs
The plug locations are as follows: The speedo pickup plugs into the back of the green plug. I don’t know offhand which pin it is connected to, but it is on one side and it is keyed. The brake connector goes all the way to the front left part of the passenger side foot well, where it plugs into the Accessory socket. The plug and socket are keyed, so as long as you’re in the general area, you shouldn’t get it wrong. If you got the wrong harness, this is irrelevant because it simply won’t fit into your car no matter how much you try.
If you have an automatic, this may apply to you: There is a connection from the wiring harness that connects to a relay mounted on the steering column on automatic cars. I think this is for the neutral disconnect switch, but I don’t know. The only reason I mention this is because my harness came from an automatic, and I didn’t know what to do about the relay until I looked in a manual car and saw that there was no relay.
Ground Wire
Unscrew the bolt holding the all the brown wires to the chassis. Then offer your new ground wire up to the bundle, and rebolt the whole lot securely.
Control Lever
Don’t worry, this one is really easy. Remove the M5 phillips screw that holds the windscreen wiper control lever. Fit the actuator arm and replace the screw. Then plug the connector together, and use cable ties to hold the connector to the steering column.
Clutch switch
This is probably the most difficult step, and for what you get, I don’t think it’s worth it. Still, here’s the description. The bracket is bolted to a support that is directly between the brake and clutch pedal stalks. This makes it extremely difficult to fit. If you can, get someone to hold the brake pedal back with a long pole so you can access the M6 bolt (M10 socket). When you have access, you need to offer up the bracket so that the mounting tab locks in place to prevent it from rotating, so that you can then fit and tighten the bolt. You normally have to do this while dangling upside down in the footwell, which isn't particularly fun. Once the switch is in place, plug it in.
Clutch Switch bypass
Automatics (or standards who don’t want the hassle of fitting the clutch switch & bracket): Plug the bridge connector into the appropriate plug of the loom, and tuck it away somewhere safe.
Refitting
Once all that's done, you can go through the laborious process of refitting your dash cluster, steering wheel and trim panels, so that you can take the car out for a test drive!
Original document by Alex Horvath. All rights remain with the original author.
